Teach your baby the sign for the word again in baby sign language with the following descriptions and videos.
Hold one flat hand in front of the body with the palm facing up. Form the other hand into a flat O and tap the fingertips onto the palm of the flat hand.
ASL pro: http://www.aslpro.com/
Beyer, Monica. 2006. Baby talk: A guide to using basic sign language to communicate with your baby. New York: Jeremy P. Tarcher/Penguin.